The well designed, standardized aptitude tests take years to develop and refine. They are copyrighted psychometric instruments available to registered professionals on a per use fee basis. These should not be available free on the Net. They come with scoring key that enable professionals to interpret the results. Sorry, but it takes expertise to use such tests. A modest investment in a proper assessment is your best route to finding. a good match between your skills and interests and a proposed course of study in which you will be expected to invest both time and money. Good luck to you.